Optical disc capable of recording address information with the same modulation on sides of adjacent grooves

ABSTRACT

An optical disc medium includes a land and a groove at which information can be recorded. A predetermined number of address information units which record address information of the land or groove are provided in a circumferential direction of the optical disc medium. The address information unit of the land includes three or more address recording areas capable of recording address information. The address information is recorded on one area selected from among the three or more address recording areas. The address information unit of the land has address information which is recorded, in the same modulation, on the side of the inner adjacent groove and on the side of the outer adjacent groove. The one area to be selected from among the three or more address recording areas for recording the address information of the land is different among three address information units adjacently arranged in a radial direction.

BACKGROUND

1. Technical Field

As described above, according to the optical disc of the presentembodiment, since the phase difference of the grooves on the both sidesof the land is set to 90 degrees or less, the maximum variation of thetrack width of the land can be decreased to approximately 70% of thecase of the optical disc having the phase difference of the adjacentwobbles which is 90 degrees.

2. Related Art

In a field of video technology, optical discs such as DVD, BD (Blu-ray(registered trademark) Disc), and the like are well-known. These opticaldiscs are used as media for recording video data and also used asexternal storage media for personal computers. As external storage mediafor personal computers, hard disks, flash memories, and the like arealso used. Compared with such media, the optical disc media haveadvantages of long-life, high reliability, and no power necessary forretaining data. In view of the advantages, the optical disc mediaattract attention as archive media for storing important data, which ismanaged by data centers and the like. However, even an optical discBD-XL which is one of the optical discs having the largest storagecapacity, has a storage capacity of 128 GB per one disc. Therefore, anumber of optical discs are required to store significantly large amountof data, and thus, a large space for storing such optical discs isrequired. Accordingly, it is required to further increase recordingdensity of optical disc media (for example, JP 2004-265546 A).

SUMMARY

In a conventional optical disc medium, address information indicating aphysical location of storing information in the optical disc medium isrecorded by pits or grooves. With the improvement of the recordingdensity of optical disc medium, it is required to develop recordingtechnology of address information which is adapted to the improvement ofthe recording density. In particular, recording technology of addressinformation enables reduction of influence on recording of user datawhile ensuring reliability of detection of address information.

One non-limiting and exemplary embodiment provides an optical discmedium and an optical disc device which achieve high recording density,which ensure reliability of detection of address information, and whichreduce influence on recording of user data.

In a first aspect, an optical disc medium is provided including a landand a groove at which information can be recorded. In the optical discmedium, a predetermined number of address information units which recordaddress information of the land or groove are provided in acircumferential direction of the optical disc medium. The addressinformation unit of the land includes three or more address recordingareas capable of recording address information, the address informationis recorded on one area selected from among the three or more addressrecording areas. The address information unit of the land has addressinformation which is recorded, in the same modulation, on the side ofthe inner adjacent groove and on the side of the outer adjacent groove.The one area to be selected from among the three or more addressrecording areas for recording the address information of the land isdifferent among three address information units adjacently arranged in aradial direction.

In a second aspect, an optical disc medium is provided including a landand a groove at which information can be recorded. In the optical discmedium, a predetermined number of address information units which recordaddress information of the land or groove are provided in acircumferential direction of the optical disc medium. Wobbles are formedon the land or groove. The wobbles include a base wobble and aninformation wobble indicating a predetermined logical value. The addressinformation unit records the address information with the informationwobble in the wobbles on the land or groove. The information wobble hasa waveform with a phase different from that of a waveform of the basewobble by approximately −90 or +90 degrees to represent “0” or “1”. Thewaveform with a phase different by approximately −90 or +90 degrees isformed by a wobble with a frequency 1.25 or 0.75 times the frequency ofthe base wobble.

In a third aspect, an optical disc device is provided, that reproducesinformation from the aforementioned optical disc medium. The opticaldisc device includes: a signal generating unit configured to generate asignal in accordance with the wobbles formed on the land or groove; aphase-shifted waveform generating unit configured to generate a signalhaving a phase difference of 90 degrees with respect to the base wobble,from the signal generated by the signal generating unit; a phasedetection unit configured to perform phase detection by using the signalgenerated by the signal generating unit and the signal generated by thephase-shifted waveform generating unit to generate an signal; an areadetermining unit configured to determine one area on which addressinformation is recorded from (a plurality of (ex. the three or more)address recording areas, according to an absolute value of a signalgenerated by the phase detection unit; and an address detection unitconfigured to detect an address from the area determined by the areadetermining unit based on a detection result of the phase detectionunit.

In a fourth aspect, a method of reproducing information from theaforementioned optical disc medium is provided. The method includes:generating a wobble signal in accordance with the wobbles formed on theland or groove; generating a signal having a phase difference of 90degrees with respect to the base wobble, from the generated wobblesignal; performing phase detection by using the wobble signal and thesignal having the phase difference of 90 degrees to generate a signal;determining one area on which address information is recorded from aplurality of (ex. the three or more) address recording areas, accordingto an absolute value of a signal generated by the phase detection; anddetecting an address from the determined area based on a result of thephase detection.

According to the present disclosure, variation of track width of theland or groove can be reduced. Therefore, an optical disc medium and anoptical disc device can be provided, which can ensure reliability ofdetection of address information and reduce influence on recording ofuser data while achieving improvement in density.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of an optical disc medium according to anembodiment.

FIG. 2 is a perspective view of a recording surface of the optical discmedium according to the embodiment.

FIG. 3 is a drawing for describing configuration of an addressinformation unit (ADIP) of the optical disc medium according to theembodiment.

FIGS. 4A to 4D are drawings for describing wobble shapes having addressinformation according to the embodiment.

FIGS. 5A to 5C are drawings for describing variation of land track widthwith respect to phases of grooves on both sides of a land.

FIG. 6 is a drawing for describing arrangement of ADIPs according to theembodiment.

FIG. 7 is a block diagram of an optical disc device according to anembodiment.

FIG. 8 is a drawing for describing configuration and operation of awobble processor according to the embodiment.

FIG. 9 is a flowchart for describing operation of address reproductionby the optical disc device according to the embodiment.

DETAILED DESCRIPTION

With reference to the drawings as required, embodiments are described indetail below. However, unnecessarily detailed description may beomitted. For example, detailed description of already well-known mattersand repeated description of substantially the same configuration may beomitted. Such omissions are intended to prevent the followingdescription from being construed unnecessarily redundant, therebyfacilitating understanding by those skilled in the art.

The inventor(s) provide the accompanying drawings and the followingdescription for those skilled in the art to help them to fullyunderstand the present disclosure and do not intend to limit the subjectdescribed in the claims by the accompanying drawings and the followingdescription.

Specific Problems to be Solved by Present Disclosure

An optical disc has a guide groove called “groove” provided for allowingprecise control of the light spot to be positioned on a recording track.User data is recorded at the groove (guide groove). There is atechnology of land-and-groove recording that ensures high recordingdensity of optical medium. The land-and-groove recording is a technologyfor recording user data not only on a groove, but also on a so-called“land” formed between areas at which the groove is formed.

The optical disc is recorded a physical address (hereinafter referred toas “address”) associated with its location for recognition of thelocation to/from which user data is recorded/reproduced. There is amethod that uses pre-pits among plural methods for forming addressinformation in the optical disc. Since user data cannot be recorded on aportion where the pre-pits are formed, the recording capacity decreasesas the address information is provided more.

In addition, as another method for forming address information, there isa method that uses a meandering (hereinafter referred to as “wobble”) ofa track. An address recorded on a wobble is referred to as “wobbleaddress”. The method that uses wobbles permits detection of the wobbleaddress by a method different from a method of reproducing user data,and thus the method that uses wobbles has an advantage that therecording capacity does not decrease.

As described above, on a groove, address information is recorded withpre-pit or wobble. However, for recording addresses on the land, theshape of a land cannot be directly controlled in a process ofmanufacturing an optical disc. Therefore, it is difficult to recordaddress information on the land, and it may be necessary to recordaddress information of the land by using the shape of the grooveadjacent to the land.

As a method for recording address information of a land by using wobblesof a groove, the following technology can be considered. For example, inan optical disc, in order to dispose address information on a land, afirst address information area and a second address information area areprovided by unit of segment. One bit of address is recorded on eitherone of the first address information area and the second addressinformation area. Specifically, a bit of “0” or “1” is recorded byforming wobbles of grooves on both sides of the land in the same phaseor the opposite phase.

The first address information area and the second address informationarea are alternately used as an area which records an address, for everyadjacent land track. Further, a selection signal is recorded, indicatingwhich one of the first and second address information is effective(which one is to be used). Hence, it is possible to record addressinformation of the land by the wobble of the groove track.

In the optical disc described above, the address of the groove is notdisposed on an area of the groove adjacent to an area of the land onwhich the address of the land is disposed. However, the address of thegroove is disposed on an area of the groove which is adjacent on theinner or outer circumferential side of the land to an area of the landon which the address of the land is not disposed.

When the adjacent grooves (namely, the groove on the outercircumferential side and the groove on the inner circumferential side)have the same shape, there is no problem. However, when they havedifferent shapes from each other, there is a problem. Namely, thedifferent shapes imply that phases of the two grooves on the outercircumferential side and on the inner circumferential side are oppositeto each other. In this case, the track width of the land (namely, thedistance between the grooves) varies in a large range, causing adverseeffects on the recording and reproducing of user data.

Further, when detection of a selection signal indicating whichinformation is effective between the first address information and thesecond address information fails, incorrect address information may bedetected. This causes a reliability problem in address detection.

An embodiment of an optical disc medium and an optical disc device tosolve the above-described problem is described below.

First Embodiment

Referring to the drawings, an optical disc medium and an optical discdevice according to the present embodiment are described.

1. Optical Disc Medium

FIG. 1 is a drawing for describing configuration of tracks of an opticaldisc medium according to the present embodiment. As shown in FIG. 1, anoptical disc 101 has a groove track (hereinafter referred to as“groove”) 102 which is formed in a spiral shape. A land track(hereinafter referred to as “land”) 103 is formed in a spiral shape at aregion sandwiched by the groove 102 formed in the spiral shape. Theoptical disc 101 of the present embodiment can record user data(information) on both of the groove 102 and the land 103. That is, thegroove 102 and the land 103 can be used as recording tracks.

The groove 102 and the land 103 are divided into a plurality of units ata predetermined angle (namely, at a predetermined range of a centralangle) in the circumferential direction. Each unit of the divided groove102 and the divided land 103 forms an address information unit(hereinafter referred to as “ADIP (ADress In Pre-Groove)”) 104 which isa unit for recording a physical address. The ADIP 104 includes one pieceof address information with respect to a unit area on the optical disc101. The ADIP 104 includes a synchronization area 105 on a header partthereof and an address information area 106 subsequent to thesynchronization area 105. This structure is repeated at the same centralangle range, from the inner circumferential side to the outercircumferential side of the optical disc 101. Further, the ADIP 104includes a plurality of ADIP units 303 (details will be describedlater).

FIG. 2 is a drawing illustrating an enlarged view of a part of arecording surface of the optical disc 101. On manufacturing the disc,the groove 102 is formed by transcribing a groove portion of a stamperwhich is formed in a groove shape to the recording surface. The groove102 is positioned on a side closer to a light source than the land 103.When the groove is formed on the stamper, a disc manufacturing deviceform the groove on the stamper with constant beam intensity, and thusthe groove width is substantially constant. The groove 102 in theoptical disc 101 which is formed by the transcription also has asubstantially constant track width on the whole surface of the opticaldisc 101.

The land 103 is located at a region between the grooves 102. As shown inFIG. 2, the groove 102 and the land 103 in most part thereof are formedin a meandering shape with a constant period. This meandering is “awobble”. The wobble is formed to have a shorter period than a responsespeed when a light spot 201 tracks the groove 102 or the land 103.Therefore, variation in the relative position between the light spot 201and the groove 102 or land 103 occurs, and such variation is opticallydetected and then converted into an electrical signal, thus enablingdetection of the shape of the wobbles.

In the detection of wobbles, a clock synchronized with a detectionsignal is generated. This clock is used for detecting the physicallength and the linear velocity of the optical disc 101. In addition, theclock may be used for reproduction of recorded sub-information byvarying the wobble shape. The optical disc medium in this embodimentrecords address information with the wobbles.

In the groove 102, as described above, due to the constraints of themanufacture of discs, the track width is regulated at a constant width.However, the track width of the land 103 sandwiched by the groove 102may vary due to the phases of the wobbles on the inner circumferentialside groove adjacent to the land and on the outer circumferential sidegroove adjacent to the land.

1-1. Configuration of ADIP

Referring to FIG. 3, ADIP 104 is described in detail as follows. FIG. 3is a drawing for describing configuration of the ADIP. As shown in FIG.3, the ADIP 104 includes a predetermined number (for example, 83) ofADIP units 303. Originally, the ADIP units 303 are arranged continuouslyin the area of the ADIP 104 as shown in FIG. 1. However, for convenienceof the description, in FIG. 3 the ADIP units 303 are shown so that theADIP units 303 are separated into discrete ADIP units 303 and thediscrete ADIP units are arranged in parallel. The most part of ADIP 104are composed of base wobbles 302. A shape of the base wobble 302corresponds to one period of waveform of +cos(ωt). The base wobble 302has a waveform which varies, within one period, from the maximum inwarddisplacement, the maximum outward displacement, and to the inwardmaximum displacement.

Another part of the ADIP 104 other than the base wobbles are composed ofwobbles each having the same periods as the one period of base wobble302. Hereinafter, one period of the base wobble 302 is referred to as “awobble period”. The ADIP unit 303 has a length of fifty-six wobbleperiods.

In the first three wobble periods of the ADIP unit 303, a MSK (MinimumShift Keying) mark 301 indicating a delimitation of the ADIP unit isdisposed. The MSK mark 301 is formed of a wobble having one period ofwaveform of +cos(1.5ωt), a wobble having one period of waveform of−cos(ωt), and a wobble having one period of waveform of −cos(1.5ωt),which are joined in this order. The secondarily disposed wobble in theMSK mark 301 represented by the waveform of −cos(ωt) has a waveform ofan inverted phase (180-degree shifted phase) with respect to the basewobble 302. Therefore, phase detection based on a signal synchronizedwith the base wobble 302 enables detection of the position of the MSKmark 301.

Among the ADIP units 303, there are a ADIP unit 303 included in asynchronization area 105 of the ADIP 104, and a ADIP unit 303 includedin an address information area 106 of the ADIP 104. The ADIP units 303have specific patterns corresponding to respective given functions infifty-three wobble periods subsequent to the MSK mark 301.

Firstly, the ADIP units 303 included in the synchronization area 105 ofthe ADIP 104 are described as follows. In the synchronization area 105,a monotone ADIP unit 304, a first synchronization ADIP unit 305, asecond synchronization ADIP unit 306, a third synchronization ADIP unit307, and a fourth synchronization ADIP unit 308 are disposed.

The monotone ADIP unit 304 is composed of only base wobbles 302 exceptfor the MSK mark disposed at the head of the ADIP unit. Thisconfiguration helps stable generation of the clock synchronized with thewobbles.

The first synchronization ADIP unit 305, the second synchronization ADIPunit 306, the third synchronization ADIP unit 307, and the fourthsynchronization ADIP unit 308 are disposed for the purpose ofrecognizing the position in the ADIP 104. They are disposed on an areaclose to the header part of the ADIP 104. There is no other ADIP unithaving the same pattern in the ADIP 104.

Next, the ADIP unit 303 included in the address information area 106 ofthe ADIP 104 is described below. In the address information area 106,monotone ADIP units 304 and address information ADIP units 309 aredisposed.

The address information area 106 includes fifteen units of ADIP units,each unit including one monotone ADIP unit 304 and four addressinformation ADIP units 309.

The address information ADIP unit 309 has one bit of information. Theaddress information area 106 has sixty bits of information, since itincludes seventy-five ADIP units as a whole (that is, it includes sixtyaddress information ADIP units 309). An address information ADIP unit309 records (stores) one bit on its address information wobble 310.

This sixty bits of information may include not only address informationwhich is a physical positional information in the optical disc, but alsosub-information such as layer information for a multilayer optical disc,information relating to a condition for recording on the optical disc,copyright information, and so on, as well aserror-correction/error-detection code therefor.

The address information ADIP unit 309 includes a MSK mark 301, a basewobble 302, and an address information wobble 310. The addressinformation ADIP unit 309 has the MSK mark 301 in the first three wobbleperiods. In addition, the address information ADIP unit 309 has the basewobbles 302 in subsequent twenty-seven wobble periods. Further, theaddress information ADIP unit 309 has an address information wobbles 310in subsequent twenty-six wobble periods. The address information wobble310 is formed based on address information, of which detail is describedlater.

Wobbles on an area other than area on which the address informationwobbles 310 are similarly formed are disposed over the whole of the ADIP104 of the optical disc 101. Further, as shown in FIG. 1, the ADIPs 104are arranged on every circumferential area from the inner circumferenceto the outer circumference. For these two reasons, the wobble shapes ofthe wobbles other than the address information wobbles 310 are the samein the radial direction.

Further, a land which is sandwiched by the grooves having the same shapehas also the same shape. Therefore, the MSK mark 301 formed on theheader part of the ADIP unit, the first synchronization ADIP unit 305,the second synchronization ADIP unit 306, the third synchronization ADIPunit 307, and the fourth synchronization ADIP unit 308 on the land havethe same shape as those on the groove, respectively. Namely, the land aswell as the groove, is detectable.

1-1-1. Address Information Wobble

With reference to FIGS. 4A to 4D, the address information wobble 310 isdescribed in detail as follows. FIG. 4A is a drawing illustrating a basepattern. FIG. 4B is a drawing illustrating a pattern of addressinformation “0”. FIG. 4C is a drawing illustrating a pattern of addressinformation “1”.

The base pattern 401 is formed to have a waveform +cos(ωt) of the threeperiods of base wobbles. The pattern 402 of the address information “0”is formed to have a waveform +cos(1.25ωt) of one period, a waveform−sin(ωt) of one period, and a waveform −cos(0.75ωt) of one period. Thepattern 403 of the address information “1” is formed to have a waveform+cos(0.75ωt) of one period, a waveform +sin(ωt) of one period, and awaveform −cos(1.25ωt) of one period. In the address information patters402 and 403, a logic value is defined by the waveforms of the secondwobbles (hereinafter referred to as “information wobble”) 402 a and 403a, respectively. Therefore, the waveforms of the second wobbles(information wobbles) 402 a and 403 a in the address informationpatterns 402 and 403 allow the logical values of “0” and “1” to berecognized, respectively. The first and third waveforms are provided bytaking into consideration continuous connection to other waveforms.

FIG. 4D is a drawing illustrating an example of address informationwobbles 310 of six land tracks which are arranged in parallel in theradial direction. FIG. 4D focuses on an address information wobble 301in arbitrary one ADIP unit 303 in one ADIP 104, and shows such addressinformation wobbles 301 are arranged in the radial direction (from theinner circumference to the outer circumference of the disc). From FIG.4D, relationship of adjacent tracks can be seen. In FIG. 4D, thereference sign “G” indicates the groove, and the reference sign “L”indicates the land.

Because the address information wobbles 310 are formed based on addressinformation as described above, the address information is differentbetween the adjacent ADIPs in the radial direction of the optical disc.

The address information wobbles 310 are formed based on addressinformation which is to be assigned to the land.

As shown in FIG. 4D, the ADIP 104 includes, on the areas of the addressinformation wobble 310, a plurality of areas as areas (hereinafter alsoreferred to as “address recording area”) for being disposed wobblepatterns base on the address information. More specifically, four areasof an area A (404), an area B (405), an area C (406), and an area D(407) are disposed as the address recording areas.

In addition, on each ADIP 104, one area is set (selected) in advancefrom among the area A to the area D as an area on which the addressinformation with respect to the ADIP is actually disposed. Hereinafter,the address recording area being set (selected) as an area on whichaddress information is actually disposed is referred to as a “validaddress recording area”. Namely, in one ADIP 104, the addressinformation with respect to the one ADIP is not disposed on otheraddress recording areas different from the set (selected) addressrecording area. That is, in one ADIP 104, the same type (A to D) of theaddress recording areas are used as the valid address recording area.For example, on a certain ADIP, when the area A is set (selected) as avalid address recording area, the address information for that ADIP isnot disposed on the areas B to D.

Exemplary states that the address information wobbles 310 have addressinformation in this embodiment are described below.

In the example shown in FIG. 4D, focusing on the land tracks, the landsL1 to L6 are arranged in an order, from the inner circumference. In theland L1, the valid address recording area is the area A (404) whichrecords (stores) address information “0”. In the land L2, the validaddress recording area is the area B (405) which records addressinformation “1”. In the land L3, the valid address recording area is thearea C (406) which records address information “1”. In the land L4, thevalid address recording area is the area D (407) which records addressinformation “0”. In the land L5, the valid address recording area is thearea A (404) which records address information “1”. In the land L6, thevalid address recording area is the area B (405) which records addressinformation “0”. In this manner, the valid address recording area isselected so that the types of the valid address recording areas aredifferent between the lands arranged adjacently in the radial direction.

In the land L1, the pattern 402 of the address information “0” isdisposed on the area A (404). In order to achieve this, a waveform of+cos(1.25ωt) of one wobble period, a waveform of −sin(ωt) of one wobbleperiod, and a waveform of +cos(0.75ωt) of one wobble period are disposedon grooves G1 and G2 on both sides of the land on which the addressinformation “0” is disposed.

In the land L5, the pattern 403 of the address information “1” isdisposed on the area A (404). In this case, a waveform of +cos(0.75ωt)of one wobble period, a waveform of +sin(ωt) of one wobble period, and awaveform of +cos(1.25ωt) of one wobble period are disposed on grooves G5and G6 on both sides of the land on which the address information “1” isdisposed

In the address information wobble 310, the base wobbles 302 are disposedon a part on which address information is not disposed.

In comparison of the shape of the pattern 402 of the address information“0” and the pattern 403 of the address information “1” with the shape ofthe base wobble 302, the waveforms of the second wobbles (namely,information wobbles) 402 a and 403 a having distinctive shapes in theaddress information patters 402 and 403 are used. The information wobble402 a of the address information “0” has a phase difference of −90degrees for the base wobble 302, and the information wobble 403 a of theaddress information “1” has a phase difference of +90 degrees for thebase wobble 302.

On the other hand, the waveforms of the first and third wobble periodsof the pattern 402 of the address information “0” and the pattern 403 ofthe address information “1” have a waveform of a cosign function with aperiod of 1.25 or 0.75 times the base wobble. This is because the firstand third wobble periods are made connected to the second wobble periodwith gradual phase shift. Further, the waveforms of the first and thirdwobble periods in the pattern 402 of the address information “0” and inthe pattern 403 of the address information “1” are formed so that theyhave phase differences equal to or less than 90 degrees with respect tothe waveform of the base wobble 302.

Returning to FIG. 4D, the ADIP 104 of a certain land Ln is now focusedon. For the ADIP 104 of the land Ln+1 adjacent to the land Ln on theouter circumference side, an area next to the area which is set for theland Ln is set as a valid address recording area on which addressinformation for the land Ln+1 is disposed. Here, the order of area isarea A→area B→area C→area D→area A→ . . . . Therefore, when the area Ais set as a valid address recording area in the ADIP 104 of the land Ln,the area B is set as a valid address recording area in the ADIP 104 ofthe land Ln+1. As shown in the example of FIG. 4D, for the lands L1 toL6, the valid address recording areas are set in the order of areaA→area B→area C→area D→area A→ . . . .

In other words, in the land Ln−1 of the ADIP 104 adjacent to the land Lnfrom the inner circumferential side, an area previous to an area whichis set as an active address information area of the land Ln is set as anactive address information area of the land Ln−1. For example, if thearea A is set in the land Ln of the ADIP 104, the area D is set in theland Ln−1 of the ADIP 104.

As described above, four areas (areas A to D) are provided as areas(address recording areas) on which wobbles having address informationcan be disposed. In addition, among these areas, the valid addressrecording area on which address information is actually disposed isshifted for every land track. For this reason, the types of validaddress recording areas in the four land tracks arranged side by side inthe radial direction are different from each other.

Such an arrangement of the address recording areas (address information)allow in any areas of the land, an area on both side of which wobbleshaving address information (the pattern 402 of the address information“0”, the pattern 403 of the address information “1”) are formed not toexist on an area other than an area that actually has addressinformation.

In other words, the area selected as an area (active address informationarea) on which address information is actually disposed is shiftedsequentially in the circumferential direction, for lands adjacent to inthe radial direction. Therefore, the waveform of the wobble providingaddress information on one land does not affect a wobble providingaddress information on another land neighboring the one land in theradial direction. Thus, the shape of the wobble of the groove adjacentto the land on which address information is disposed on the innercircumferential side of the land and the shape of the wobble of thegroove adjacent to the land on the outer circumferential side can bein-phase, so that variation of the groove width can be suppressed.

In the optical disc medium according to the present embodiment, fourareas (areas A to D) on which address information can be recorded areprovided, and an area to be selected from the four areas as an validaddress recording area is shifted by one for every track. However, thenumber of the areas that can record address information is not limitedto three, but the number can be three or more. If the number of theareas that can record address information is three or more, the waveformof the wobble providing address information on one land does not affectwobbles providing address information on the other lands neighboring theone land in the radial direction, achieving the above-mentioned effects.

As described above, the optical disc 101 according to the presentembodiment is an optical disc medium in which information can berecorded on a land and groove thereof. In the optical disc 101, apredetermined number of ADIPs 104 are provided in a circumferentialdirection of the optical disc 101, where the ADIPs 104 are addressinformation units which record (or store) address information of theland or groove. Each ADIP 104 includes three or more address recordingareas (for example, the area A (404), the area B (405), the area C(406), the area D (407)) on which address information can be recorded,and the address information is recorded on one area (valid addressrecording area) selected from among the three or more address storingareas. The one area (valid address recording area) selected from amongthe three or more address storing areas for recording the addressinformation is different among three address information units arrangedside by side in the radial direction.

According to the configuration as above, a wobble formed on one trackfor recoding address information does not affect address information onanother track adjacent in the radial direction. Therefore, the shape ofthe waveform of the wobble on the one track can be determined accordingonly to the address information on the one track without consideringaddress information of the adjacent tracks, and thus, variation of thetrack width can be suppressed. Accordingly, high recording density canbe achieved, reliability of detection of address information can beensured, and influence on recording of user data can be reduced.

In addition, the optical disc 101 according to the present embodiment isan optical disc medium in which information can be recorded on a landand groove thereof. In the optical disc 101, a predetermined number ofADIPs 104 are provided in a circumferential direction of the opticaldisc medium, where the ADIPs 104 are address information units whichrecord address information of the land or groove. Wobbles are formed onthe land or groove. The wobbles include a base wobble 302 andinformation wobbles 402 a and 403 a indicating predetermined logicalvalues. In the ADIP 104, the address information is recorded with theinformation wobbles 402 a and 403 a in the wobbles on the land orgroove. The information wobbles 402 a and 403 a are formed to havewaveforms with phase differences of −90 to +90 degrees with respect tothe waveform of the base wobble.

The phase difference of the waveform between the information wobble andthe base wobble from −90 to +90 degrees allows the phase difference ofthe waveforms on the both sides of the land or groove on which wobble isformed to be suppressed within 90 degrees at most. Accordingly, thevariation of the track width can be suppressed, and thus, high recordingdensity can be achieved, reliability of detection of address informationcan be ensured, and influence on recording of user data can be reduced.

1-2. Variation of Land Track Width

With reference to FIGS. 5A to 5C, variation of the land track width forphases of the groove on both sides of the land is described below. FIGS.5A to 5C are drawings illustrating a form of wobbles, in three wobbleperiods, of the track sandwiched by the grooves. FIG. 5A is a drawingillustrating two grooves G1 and G2 having the same phase of wobbles anda land L between the grooves G1 and G2. FIG. 5B is a drawingillustrating two grooves G1 and G2 having the opposite phase of wobbles(phase difference is 180 degrees) and a land L between the grooves G1and G2. FIG. 5C is a drawing illustrating the two grooves G1 and G2having phase difference in wobbles by 90 degrees and a land L betweenthe grooves G1 and G2.

In FIG. 5A, the phases of the grooves G1 and G2 on the both sides of theland L are in-phase and the inner groove G1 and the outer groove G2 varysynchronized with each other. Thus, the variation Δw of the width of thetrack of the land L is zero as shown in the following equation, namely,the width of the track is constant.Δw=a·cos(ωt)−a·cos(ωt)=0

In FIG. 5B, at a position where the inner groove G1 has a maximumdisplacement in the inward direction, the outer groove G2 has a maximumdisplacement in the outward direction, and therefore, the land L has themaximum track width at the position. Contrary, at a position where theinner groove G1 has a maximum displacement in the outward direction, theouter groove G2 has a maximum displacement in the inward direction, andtherefore, the land L has the minimum track width at the position.Accordingly, the variation in difference Δw of the track width changesdepending on the position in the circumferential direction, as shown inthe following equation.Δw=a·cos(ωt)−(−a·cos(ωt))=2a·cos(ωt)

In FIG. 5C, since the phase difference is 90 degrees, the variation indifference of the track width can be suppressed to be smaller than thatof the case of the phase difference of 180 degrees. Specifically, thevariation in difference Δw of the land track width becomes 0.7 timesthat of the case (FIG. 5B) of the phase difference of 180 degrees, asshown in the following equation.Δw=a·cos(ωt)−a·sin(ωt)=√{square root over (2)}a·sin(ωt−π/4)

As described above, according to the optical disc of the presentembodiment, since the phase difference of the grooves on the both sidesof the land is set to 90 degrees or less, the maximum variation of thetrack width of the land can be decreased by approximately 70% of thecase of the optical disc having the phase difference of the adjacentwobbles which is 90 degrees.

1-3. Assignment of Address Information Area in ADIP

FIG. 6 shows a drawing for describing assignment of the selected areas Ato D on each ADIP in the optical disc of the present embodiment. Asshown in FIG. 6, an ADIP 601 in which the area A is selected as an areaon which address information is disposed, an ADIP 602 in which the areaB is selected, an ADIP 603 in which the area C is selected, and an ADIP604 in which the area D is selected are arranged in this order in thecircumferential direction.

In the optical disc of the present embodiment, the area (A to D) to beselected as an area on which address information is disposed is shiftedin order in accordance with the arrangement order of the ADIPs 104. Thisarrangement allows easy anticipation of the area selected on thesubsequent ADIP 104 on the basis of the area on the preceding ADIP 104selected as an area on which address information is disposed.

In addition, one track (one circuit) is divided in the circumferentialdirection at equal angle intervals into a plurality (for example, nine)of ADIPs, and the number of the ADIPs per one circuit is set to anintegral multiple of the number of selectable areas (for example, four)plus one (for example, set to nine ADIPs). With this arrangement, thearea selected as an area on which address information is disposed isshifted by one area for every circuit, for an ADIP arranged in theregion having the same central angle on the next or previous track.

That is, the area is shifted by one for every track. This arrangement isachieved by setting the number of the ADIPs per one circuit to anintegral multiple of the number of the selectable areas (for example, 4)plus one. For example, when the number of the areas selectable as anarea on which address information is disposed is set to three, thenumber of the ADIPs per one circuit can be set to ten so that the sameeffects can be achieved as in the case that the number of the selectableareas is four.

Further, in order to achieve a configuration that the selected area isdifferent among the lands on three tracks arranged side by side in theradial direction, the number of the ADIPs per one circuit and the numberof the selectable areas may be set to be coprime to each other.

As described above, according to the optical disc 101 of the presentembodiment, in the ADIPs 104 which are address information unitsspirally arranged, the number (for example 9) of the ADIPs 104 includedin one circuit (one track) and the number (for example, 4) of the areas(areas A to D) of one ADIP 104 on which address information is disposedare coprime to each other.

In the optical disc of the present embodiment, the wobbles havingaddress information have phase differences of 90 degrees with respect tothe base wobble 302. However, the phase difference may be equal to orless than 90 degrees. When the phase difference are equal to or lessthan 90 degrees, the smaller the phase difference is, the smaller thevariation of the land track width is, and therefore, greater effects canbe expected. In this case, however, detection performance of the addressinformation may deteriorate, and to avoid this, for example, the phasedifference may be set to certain degree that can ensure reliability ofthe address information.

According to the configuration of the optical disc medium of the presentembodiment, the ADIPs 104 are arranged in a radial direction andspirally from the inner circumferential side to the outercircumferential side with the same central angle. However, apredetermined zone may be set in each of predetermined ranges in aradial direction, and the same configuration as that of the optical discof the present embodiment may be applied to the predetermined zone ineach range in a radial direction. This can also achieve the sameeffects.

2. Optical Disc Device

An optical disc device that records information on and reproducesinformation from the optical disc 101 according to the presentembodiment is described below. FIG. 7 is a block diagram of the opticaldisc device according to the present embodiment.

The optical disc device includes an optical head 701, a servo controller702, a signal generator 703, a wobble processor 704, an address timinggenerator 705, a reproduction processor 706, a decoder 707, and acontroller 711. The optical disc device further includes an encoder 708,a recording processor 709, and a laser driver 710.

The optical disc 101 is inserted into the optical disc device. Theoptical head 701 irradiates a light beam on the optical disc 101. Thelight beam is reflected on the optical disc 101, and the reflected lightis converted by a photo detector (not shown) into an electrical signalhaving a voltage level representing information on the reflected lightamount. The photo detector is included in the optical head 701. Thephoto detector is composed of four separate photo detectors which arearranged in four regions divided in the track groove direction(tangential direction) and the radial direction (radial direction).

Based on electrical signals output from the separate photo detectors,the signal generator 703 generates a focus error signal, a trackingerror signal, a wobble signal, and an addition signal.

The addition signal is the sum of all the signals from the four separatephoto detectors, and represents the reflected light amount itself fromthe optical disc. The focus error signal is a signal which is, forexample, detected by the astigmatic method. The focus error signal isobtained as follows. Specifically, in each of pairs of the separatephoto detectors arranged in the diagonal directions, signals from theseparate photo detectors are summed. Then the subtraction is performedbetween the summed signal of one pair and the summed signal of the otherpair to obtain the focus error signal.

The tracking error signal and the wobble signal are signals detected bythe push-pull method. The tracking error signal and the wobble signalare obtained as follows. Specifically, in each of pairs of the separatephoto detectors arranged in the tangential direction, the two signalsfrom the separate photo detectors are summed. Then subtracting isperformed between the summed signal of one pair and the summed signal ofthe other pair to obtain each of the tracking error signal and thewobble signal.

The tracking error signal is generated by extracting a frequencycomponent in a range from 0 Hz to several tens of kilohertz from apush-pull signal. The wobble signal is generated by extracting a signalcomponent in a range from several tens of kilohertz to several megahertzfrom the push-pull signal.

The servo controller 702 moves upwardly and downwardly an objective lensin the optical head 701 so that the focus error signal becomes zero, tocollect a light spot on a recording surface. In addition, the servocontroller 702 drives the objective lens in the radial direction so thatthe tracking error signal becomes zero, to cause the light spot to trackthe land or groove.

Whether the tracking is performed on the land or on the groove isdetermined in accordance with whether to drive the light spot to theouter circumference or the inner circumference based on the trackingerror. This driving direction is determined according to instructionsfrom the controller 711.

The signal generator 703 is a signal generating unit. The wobbleprocessor 704 processes a wobble signal generated by the signalprocessor 703. The wobble processor 704 generates a wobble clock bymultiplying a reproduction signal on an area of base wobbles 302 in thewobble signal, detects ADIP synchronization, and reproduce addressinformation.

The address timing generator 705 generates timing for reproductionprocessing from various signals generated by the wobble processor 704 tooutput the timing to the reproduction processor 706. Similarly, theaddress timing generator 705 generates timing for recording processingfrom various signals generated by the wobble processor 704 to output thetiming to the recording processor 709. At this time, the address timinggenerator 705 uses a target address which is instructed from thecontroller 711.

For the reproduction of the user data, each of components operates asfollows. First, the reproduction processor 706 extracts binary data fromthe addition signal generated by the signal generator 703, in accordancewith the timing of a reproduction target address generated by theaddress timing generator 705. Then, the decoder 707 decodes the binarydata and performs error correction on the decoded data, and then outputthe error-corrected decoded data as reproduction data.

For the recording of the user data, each component operates as follows.First, the encoder 708 receives recoding data and adds error-correctioncode to the recording data, and then encodes the recording data tobinary data. The recording processor 709 sends the laser driver 710 aninstruction for recording power of light emission, according to thetiming of the recording target address generated by the address timinggenerator 705.

2-1. Wobble Processor

With reference to FIG. 8, the wobble processor 704 of the optical discdevice according to the present embodiment is described in detail below.

The wobble processor 704 includes an ADIP synchronization detector 801,a timing generator 802, first to fourth integrators 803 to 806, amaximum value area detector 807, and an area determination unit 808. Thewobble processor 704 further includes a wobble PLL 809, a multiplier810, an absolute value detector 811, an integrator 812, a comparator813, and an address information determination unit 814.

A wobble signal is input from the signal generator 703 to the wobbleprocessor 704. The wobble PLL 809 multiplies a reproduction signal fromthe base wobble 302 to generate a wobble clock. Simultaneously, thewobble PLL 809 generates a 90-degree phase-shifted waveform which hasthe same frequency as the base wobble 302 and has a phase shifted by +90degrees from the phase of the base wobble 32. Namely, the wobble PLL 809is an example of a phase-shifted waveform generating unit.

In this embodiment, the 90-degree phase-shifted waveform is a sinewaveform, but it may be other waveforms. For example, it may be arectangular waveform, triangular waveform, and so on, and thesewaveforms can achieve the same functions as the sine waveform. Such awaveform may be selected for the simplicity of circuit design. Themultiplier 810 multiplies the 90-degree phase-shifted signal generatedby the wobble PLL 809 by the wobble signal to output the signalgenerated by the multiplication. The absolute value detector 811 outputsthe absolute value of the output from the multiplier 810. The absolutevalue detector 811 outputs 0 for the wobble signal of the base pattern,and outputs a value other than 0 for the wobble signal of the pattern ofthe address information “0” or the address information “1”.

On the other hand, the ADIP synchronization detector 801 searches asignal on the synchronization area 105 in the optical disc 101 from thewobble signal to output an ADIP synchronization signal synchronized withthe ADIP.

The timing generator 802 counts the wobble clock generated by the wobblePLL 809 up to a certain number to generates a timing signal indicatingeach of the areas A to D. These timing signals are output for everyaddress information wobbles 310 in the ADIP 104.

The first to fourth integrators 803 to 806 are reset at the boundary ofthe ADIPs 104, and integrate the output signal from the absolute valuedetector 811 in synchronization with the timings of the area A to thearea D generated by the timing generator 802 to output the results,respectively. Hence the first to fourth integrators 803 to 806 integratethe signals from the areas A to D to output the results, respectively.

The maximum value area detector 807 is an example of an addressinformation searching unit. The maximum value area detector 807 detectswhich integrator among the first to fourth integrators 803 to 806outputs the maximum value, and outputs the detected result. The processof detecting the maximum value area is performed based on the results ofthe integration processes over the whole of the ADIP, and thus thesearching of the area on which address information is recorded can beperformed with high reliability.

The area determination unit 808 is an example of an area determinationunit. The area determination unit 808 determines one area from among theareas A to D, as an area on which the address information is disposed,at a boundary of the subsequent ADIPs, based on the output from themaximum value area detector 807. At this time, the area determinationunit 808 determines the area of the subsequent ADIP, based on the outputfrom the maximum value area detector 807 on the preceding ADIP 104 atthe ADIP boundary timing. Specifically, when the output from the maximumvalue area detector 807 on the preceding ADIP 104 at the ADIP boundarytiming indicates the area A, the area B is anticipated for thesubsequent ADIP, and therefore, the area determination unit 808 selectsthe area B. Similarly, when the area B is determined for the precedingADIP, the area C is selected for the subsequent ADIP. Similarly, whenthe area C is determined for the preceding ADIP, the area D is selectedfor the subsequent ADIP. Similarly, when the area D is determined forthe preceding ADIP, the area A is selected for the subsequent ADIP.

The selector 815 selects a timing signal of the area selected by thearea determination unit 808 to output it. The integrator 812 integratesthe output signal from the multiplier 810 to output the result inaccordance the timing signal selected by the selector 815. The operationby the configuration of the multiplier 810 and the integrator 812 isgenerally known as means for phase detection. That is, the configurationof the multiplier 810 and the integrator 812 is an example of a phasedetection unit.

The comparator 813 binalizes the output from the integrator 812 at theend of the address information wobble 310. The address informationdetermination unit 814 is an example of an address information searchingunit. The address information determination unit 814 determines addressinformation based on the output result of the comparator 813 for all ofthe address information wobbles 310 of the ADIP 104, and outputs it asaddress information.

FIG. 9 is a flowchart of operation of reproducing the addressinformation in the optical disc device according to the presentembodiment. With reference to the flowchart in FIG. 9, the operation ofthe address information reproduction of the optical disc device of thepresent embodiment is described below. When the reproduction of theaddress information is started, the ADIP synchronization detector 801performs ADIP synchronization for determining a position of the ADIP 104(S1).

Once the ADIP synchronization is established, it becomes possible togenerate the timing of the areas A to areas B. Then, the timinggenerator 802, the first to fourth integrators 803 to 806, and themaximum value area detector 807 search for the address recording areas(S2). This process (S2) is performed until reaching the ADIP boundary(S3). When reaching the ADIP boundary, the maximum value area detector807 determines the area of the preceding ADIP (S4).

Then, the area determination unit 808 determines the area of thesubsequent ADIP (S5). The selector 815 selects the timing of thedetermined area. Then the integrator 812, the comparator 813, and theaddress information determination unit 814 performs address detection inthe determined area (either one of areas A to D).

Other Embodiments

As described above, the first embodiment is described as examples of theart disclosed in the present application. However, the art in thepresent disclosure is not limited thereto, and is also applicable tovarious embodiments to which modifications, substitutions, additions, oromissions, etc. is suitably applied.

For example, in the above example, the pattern shown in FIG. 4B is thepattern of the address information “0”, and the pattern shown in FIG. 4Cis the pattern of the address information “1”, however, the patternsettings may be vice versa. That is, the pattern shown in FIG. 4B may bethe pattern of the address information “1”, and the pattern shown inFIG. 4C may be the pattern of the address information “0”.

In addition, as shown in the address information patters 402 and 403 inFIGS. 4B and 4C, the number of the information wobble 402 a and 403 a(±sin(ωt)) is one, however, it may be plural (two or more) (for example,six), in consideration of the viewpoint of the reliability. For example,the pattern of the address information “0” may be formed by acombination of a waveform of +cos(1.25ωt) of one period, a waveform of−sin(ωt) of 6 periods, and a waveform of −cos(0.75ωt) of one period.Similarly, the pattern of the address information “1” may be formed by acombination of a waveform of +cos(0.75ωt) of one period, a waveform of+sin(ωt) of 6 periods, and a waveform of −cos(1.25ωt) of one period.

In addition, each component of the optical disc device described in theembodiment above may be realized as a dedicated electronic circuit(hardware, ASIC, DSP, or the like). Alternatively, CPU, MPU, FPGA, orthe like may be programmable or reconfigurable to realize the functionsof the components of the optical disc device.

As described above, the optical disc device according to the presentembodiment includes an address information searching unit that searchesan area on which address information is formed, an area determinationunit that determines an area on which the address information is formedbased on the result of the address information searching unit, and anaddress information detection unit that detects an address from the areadetermined by the area determination unit.

In addition, the optical disc device according to the present embodimentincludes a signal generating unit that generates a signal correspondingto a wobble of a track, a 90-degree phase-shifted waveform generatingunit that generates a signal having a phase difference of 90 degreeswith respect to the base wobble, from the signal generated by the signalgenerating unit, a phase detection unit that detects a phase by usingthe signal generated by the 90-degree phase-shifted waveform generatingunit, and an address information detection unit that detects an addressbased on the detection results of the phase detection unit.

As described above, embodiments are described as examples of the artaccording to the present disclosure. For that, the accompanying drawingsand the detailed descriptions are provided.

Accordingly, the components described in the accompanying drawings andthe detailed description for exemplifying the art as described above mayinclude not only components which are necessary to solve the problem,but also components which are unnecessary to solve the problem.Therefore, it should not immediately be construed that the unnecessarycomponents are necessary even though such unnecessary components aredescribed in the drawings or the description.

In addition, the embodiments as described above are to exemplify the artin the present disclosure, and therefore, the embodiments can be appliedvarious kinds of modifications, substitutions, additions, omissions, andso on, provided that they fall within the scope of the claims orequivalents thereof.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable to a recording medium that recordsphysical addresses on a groove of track, and to a device for recordingand/or reproducing data on such a recording medium. More specifically,the present disclosure is applicable to an optical disc medium and anoptical tape, and to a device for recording and/or reproducing data onthe optical disc or tape, and the like.

What is claimed is:
 1. An optical disc medium comprising a land and agroove at which information can be recorded, wherein a predeterminednumber of address information units which record address information ofthe land or groove are provided in a circumferential direction of theoptical disc medium, the address information unit of the land includesthree or more address recording areas capable of recording addressinformation, the address information is recorded on one area selectedfrom among the three or more address recording areas, the one area to beselected from among the three or more address recording areas forrecording the address information of the land is different among threeaddress information units adjacently arranged in a radial direction,wobbles are formed on the land and the groove, the wobbles include abase wobble and an information wobble indicating a predetermined logicalvalue of 0 or 1, the address information is recorded with the logicalvalue of the information wobble, the logical value 0 of the informationwobble is represented by a waveform having a phase different from aphase of the base wobble by about −90 degree, and the logical value 1 ofthe information wobble is represented by a waveform having a phasedifferent from a phase of the base wobble by about +90 degree, thewobble of the groove adjacent to a land on the inner circumference sidehas the same waveform as the wobble of the groove adjacent to the landon the outer circumference side, and variation of track width of theland or groove is suppressed to a predetermined range.
 2. The opticaldisc medium according to claim 1, wherein the predetermined range is 70%of a width of a track having a waveform with a phase that is differentfrom a phase of the base wobble by 180 degrees.
 3. The optical discmedium according to claim 1, wherein the number of the addressinformation units provided in the circumferential direction and thenumber of the address recording areas are coprime to each other.
 4. Anoptical disc device that reproduces information from the optical discmedium according to claim 1, comprising: a signal generator configuredto generate a signal in accordance with the wobbles formed on the landor groove; a phase-shifted waveform generator configured to generate asignal having a phase difference of 90 degrees with respect to the basewobble, from the signal generated by the signal generator; a phasedetector configured to perform phase detection by using the signalgenerated by the signal generator and the signal generated by thephase-shifted waveform generator to generate a signal; an areadetermining unit configured to determine one area on which addressinformation is recorded from the three or more address recording areas,according to an absolute value of a signal generated by the phasedetector; and an address detector configured to detect an address fromthe area determined by the area determining unit based on a detectionresult of the phase detector.
 5. A method of reproducing informationfrom the optical disc medium according to claim 1, comprising:generating a wobble signal in accordance with the wobbles formed on theland or groove; generating a signal having a phase difference of 90degrees with respect to the base wobble, from the wobble signal;performing phase detection by using the wobble signal and the signalhaving the phase difference to generate a signal; determining one areaon which address information is recorded from the three or more addressrecording areas, according to an absolute value of the signal generatedby the phase detection; and detecting an address from the areadetermined by the area determining unit based on a result of the phasedetection.